Surgical stapling apparatus

ABSTRACT

A surgical stapling device particularly suited for endoscopic procedures is described. The device includes a handle assembly and an elongated body extending distally from the handle assembly. The distal end of the elongated body is adapted to engage a disposable loading unit. A control rod having a proximal end operatively connected to the handle assembly includes a distal end extending through the elongated body. A control rod locking member is provided to prevent movement of the control rod until the disposable loading unit is fully secured to the elongated body of the stapling device.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.13/295,140 filed Nov. 14, 2011, which is a continuation of U.S. patentapplication Ser. No. 13/285,355 filed Oct. 31, 2011, now U.S. Pat. No.8,210,416 which is a continuation of U.S. patent application Ser. No.12/793,196 filed Jun. 3, 2010, now U.S. Pat. No. 8,070,033, issued Dec.6, 2011, which is a continuation of application Ser. No. 12/494,617filed Jun. 30, 2009, now U.S. Pat. No. 8,083,118, issued Dec. 27, 2011,which is a divisional of U.S. patent application Ser. No. 11/974,638filed Oct. 15, 2007, now U.S. Pat. No. 7,565,993, issued Jul. 28, 2009,which is a continuation of U.S. patent application Ser. No. 11/489,212filed Jul. 19, 2006, now U.S. Pat. No. 7,303,107, issued Dec. 4, 2007,which is a continuation of U.S. patent application Ser. No. 11/186,742filed Jul. 20, 2005, abandoned on Nov. 27, 2006, which is a continuationof U.S. patent application Ser. No. 10/983,288 filed Nov. 5, 2004, nowU.S. Pat. No. 6,953,139, issued Oct. 11, 2005, which is a continuationof U.S. patent application Ser. No. 10/700,250, filed Nov. 3, 2003,abandoned on Jan. 18, 2005, which is a continuation of U.S. patentapplication Ser. No. 10/014,004 filed Dec. 10, 2001, now U.S. Pat. No.6,669,073, issued Dec. 30, 2003, which is a continuation of U.S. patentapplication Ser. No. 09/680,093 filed Oct. 5, 2000, now U.S. Pat. No.6,330,965, issued Dec. 18, 2001, which is a divisional of U.S. patentapplication Ser. No. 09/561,567 filed Apr. 28, 2000, now U.S. Pat. No.6,241,139, issued Jun. 5, 2001, which is a divisional of U.S. patentapplication Ser. No. 09/166,378 filed Oct. 5, 1998, now U.S. Pat. No.6,079,606, issued Jun. 27, 2000, which is a divisional of U.S. patentapplication Ser. No. 08/935,980 filed Sep. 23, 1997, now U.S. Pat. No.5,865,361, issued Feb. 2, 1999. Each of these applications isincorporated herein in their entirety by this reference.

BACKGROUND

1. Technical Field

This application relates to a surgical stapling apparatus, and moreparticularly, to an articulating mechanism for use with an endoscopicsurgical stapling apparatus for sequentially applying a plurality ofsurgical fasteners to body tissue and optionally incising fastenedtissue.

2. Background of Related Art

Surgical devices wherein tissue is first grasped or clamped betweenopposing jaw structure and then joined by surgical fasteners are wellknown in the art. In some instruments a knife is provided to cut thetissue which has been joined by the fasteners. The fasteners aretypically in the form of surgical staples but two part polymericfasteners can also be utilized.

Instruments for this purpose can include two elongated members which arerespectively used to capture or clamp tissue. Typically, one of themembers carries a staple cartridge which houses a plurality of staplesarranged in at least two lateral rows while the other member has ananvil that defines a surface for forming the staple legs as the staplesare driven from the staple cartridge. Generally, the stapling operationis effected by cam bars that travel longitudinally through the staplecartridge, with the cam bars acting upon staple pushers to sequentiallyeject the staples from the staple cartridge. A knife can travel betweenthe staple rows to longitudinally cut and/or open the stapled tissuebetween the rows of staples. Such instruments are disclosed, forexample, in U.S. Pat. No. 3,079,606 and U.S. Pat. No. 3,490,675.

A later stapler disclosed in U.S. Pat. No. 3,499,591 applies a doublerow of staples on each side of the incision. This is accomplished byproviding a disposable loading unit in which a cam member moves throughan elongate guide path between two sets of staggered staple carryinggrooves. Staple drive members are located within the grooves and arepositioned in such a manner so as to be contacted by the longitudinallymoving cam member to effect ejection of the staples from the staplecartridge of the disposable loading unit. Other examples of suchstaplers are disclosed in U.S. Pat. Nos. 4,429,695 and 5,065,929.

Each of the instruments described above were designed for use inconventional surgical procedures wherein surgeons have direct manualaccess to the operative site. However, in endoscopic or laparoscopicprocedures, surgery is performed through a small incision or through anarrow cannula inserted through small entrance wounds in the skin. Inorder to address the specific needs of endoscopic and/or laparoscopicsurgical procedures, endoscopic surgical stapling devices have beendeveloped and are disclosed in, for example, U.S. Pat. Nos. 5,040,715(Green, et al.); 5,307,976 (Olson, et al.); 5,312,023 (Green, et al.);5,318,221 (Green, et al.); 5,326,013 (Green, et al.); and 5,332,142(Robinson, et al.).

U.S. Surgical, the assignee of the present application, has manufacturedand marketed endoscopic stapling instruments, such as the Multifire ENDOGIA* 30 and Multifire ENDO GIA* 60 instruments, for several years. Theseinstruments have provided significant clinical benefits. Nonetheless,improvements are possible, for example, by reducing the cost andcomplexity of manufacture.

Current laparoscopic linear stapling devices are configured to operatewith disposable loading units (U.S. Surgical) and staple cartridges(Ethicon) of only one size. For example, individual linear staplers arepresently available for applying parallel rows of staples measuring 30mm, 45 mm and 60 mm in length. Thus, during a normal operation, asurgeon may be required to utilize several different staplinginstruments to perform a single laparoscopic surgical procedure. Suchpractices increase the time, complexity and overall costs associatedwith laparoscopic surgical procedures. In addition, costs are greater indesigning and manufacturing multiple stapler sizes, as opposed tocreating a single, multipurpose stapler.

It would be extremely beneficial to provide a surgical device for useduring laparoscopic and/or endoscopic surgical procedures that can beemployed with several different sized disposable loading units to reducethe overall costs associated with such procedures. It would also beparticularly beneficial if the device could perform multiple tasks,using disposable loading units of varying size and of varying purpose,such as, for example, to staple, clip, cut and/or articulate.

In making improvements or modifications to the current instruments, itwould be highly desirable not to sacrifice any of the important benefitsof the MULTIFIRE ENDO GIA* 30 and 60 instruments as compared to othercommercially available products, e.g., the endoscopic staplinginstruments manufactured and marketed by Ethicon, Inc. For example, anyimprovement should advantageously provide a fresh knife blade for eachfiring of the instrument and ensure that the disposable loading unit issecurely retained in the stapling instrument unless and until theoperating team chooses to remove it. These advantages have historicallybeen found in the U.S. Surgical instruments, but not in the Ethiconinstruments.

SUMMARY

In accordance with the present disclosure, a surgical stapling apparatusfor sequentially applying a plurality of fasteners to body tissue andsimultaneously incising tissue is provided. The surgical staplingapparatus is adapted to receive disposable loading units having rows ofstaples having a linear length of between 30 mm and 60 mm. The surgicalstapling apparatus is also adapted to receive articulating andnon-articulating disposable loading units.

The surgical stapling apparatus includes a handle assembly having amovable handle and a stationary handle. The movable handle is movablethrough an actuation stroke to clamp tissue and to effect ejection ofstaples from the disposable loading unit. An elongated body extendsdistally from the handle assembly and defines a longitudinal axis. Anactuation shaft having a toothed rack is operably associated with themovable handle by a pawl mechanism. The distal end of the actuationshaft is connected to a control rod having a distal end adapted tooperatively engage an axial drive assembly located within a disposableloading unit.

The stapling apparatus includes an articulation mechanism having anarticulation lever operatively engaged with a cam member having astepped camming channel. The cam member is engaged with a translationmember which includes a pin dimensioned to be received within thestepped camming channel such that pivotable movement of the lever causeslinear movement of the translation member. A first articulation linkincludes a proximal end adapted to engage the translation member and adistal end adapted to engage a second articulation link positionedwithin the disposable loading unit. Linear movement of the translationmember causes linear movement of the articulation links to causearticulation of a tool assembly of the disposable loading unit.

The surgical stapling apparatus also preferably includes a sensingmechanism for sensing the type of disposable loading unit secured to theelongated body of the apparatus. The sensing mechanism includes asensing tube positioned within the elongated body to engage a disposableloading unit secured to the elongated body. A sensing cylinder connectedto the sensing tube engages a locking ring having a tab portionconfigured to engage the articulation mechanism in a first position toprevent movement of the articulation lever. The locking ring is moved bythe sensing cylinder when an articulating disposable loading unit issecured to the elongated body of the stapling apparatus to a secondposition to disengage the tab portion from the articulation mechanism topermit movement of the articulation lever. In contrast, anon-articulating disposable loading unit will not unlock thearticulation lever.

BRIEF DESCRIPTION OF THE DRAWINGS

Various preferred embodiments are described herein with reference to thedrawings:

FIG. 1 is a perspective view of one preferred embodiment of thepresently disclosed surgical stapling apparatus;

FIG. 2 is a top view of the surgical apparatus shown in FIG. 1;

FIG. 3 is a side view of the surgical apparatus shown in FIG. 1;

FIG. 4 is a perspective view with parts separated of the handle assemblyof the surgical apparatus shown in FIG. 1;

FIG. 5 is a cross-sectional view of a portion of the firing lockoutmechanism shown in FIG. 4;

FIG. 6 is a perspective of the slide plate of the anti-reverse clutchmechanism of the surgical apparatus;

FIG. 7 is an enlarged perspective view of the anti-reverse clutchmechanism shown in FIG. 1;

FIG. 8 is a side cross-sectional view of the surgical stapling apparatusshown in FIG. 1 in the non-actuated position with the disposable loadingunit removed;

FIG. 9 is a perspective view with parts separated of the rotationmember, the articulation mechanism, and the elongated body of thesurgical stapling apparatus shown in FIG. 1;

FIG. 10 is an enlarged view of the indicated area of detail shown inFIG. 8;

FIG. 10 a is a perspective view of the translation member of thearticulating mechanism and the proximal end of the elongated body of thesurgical stapling apparatus shown in FIG. 1;

FIG. 10 b is an enlarged cross-sectional view of the indicated area ofdetail of FIG. 8;

FIG. 10 c is a cross-sectional view along section line 10 c-10 c of FIG.8;

FIG. 11 is a perspective view of the cam member of the articulationmechanism of the surgical stapling apparatus shown in FIG. 1;

FIG. 12 is a top view of the cam member of the articulation mechanism ofthe surgical stapling apparatus shown in FIG. 1;

FIG. 12 a is a perspective view of a non-articulating disposable loadingunit usable with the surgical stapling apparatus shown in FIG. 1;

FIG. 12 b is a perspective view of the preferred articulating disposableloading unit of the surgical stapling apparatus shown in FIG. 1;

FIG. 13 is a cross-sectional view taken along section line 13-13 of FIG.10;

FIG. 14 is a cross-sectional view taken along section line 14-14 of FIG.10;

FIG. 15 is a cross-sectional view taken along section line 15-15 of FIG.10;

FIG. 16 is an enlarged view of the indicated area of detail shown inFIG. 8;

FIG. 17 is a side perspective view of the blocking plate of the surgicalstapling apparatus shown in FIG. 1;

FIG. 18 is a top perspective view of the blocking plate of the surgicalstapling apparatus shown in FIG. 1;

FIG. 19 is a perspective view of a disposable loading unit usable withthe surgical stapling apparatus of FIG. 1;

FIG. 20 is another perspective view of a disposable loading unit usablewith the surgical stapling apparatus of FIG. 1;

FIG. 21 is a perspective view of the tool assembly of the surgicalstapling apparatus of FIG. 1 with parts separated;

FIG. 22 is an enlarged perspective view of the distal end of the anvilassembly showing a plurality of staple deforming cavities;

FIG. 23 is an enlarged perspective view of the distal end of the staplecartridge of the surgical stapling apparatus shown in FIG. 1;

FIG. 24 is a side cross-sectional view taken along section line 24-24 ofFIG. 23;

FIG. 25 is a bottom perspective view of the staple cartridge shown inFIG. 21;

FIG. 26 is an enlarged perspective view of the actuation sled, thepushers and the fasteners shown in FIG. 21;

FIG. 27 is an enlarged perspective view with parts separated of theproximal housing portion and mounting assembly of the disposable loadingunit shown in FIG. 19;

FIG. 28 is an enlarged perspective view of the mounting assembly of thedisposable loading unit shown in FIG. 19 mounted to a distal end portionof the proximal housing portion;

FIG. 29 is an enlarged perspective view of the proximal housing portionand the mounting assembly of the disposable loading unit shown in FIG.19 with the upper housing half removed;

FIG. 30 is a perspective view of the proximal housing portion and themounting assembly of the disposable loading unit shown in FIG. 19 withthe upper housing half removed;

FIG. 31 is a perspective view with parts separated of the axial driveassembly;

FIG. 32 is an enlarged perspective view of the axial drive assemblyshown in FIG. 31;

FIG. 33 is an enlarged perspective view of the proximal end of the axialdrive assembly shown in FIG. 31 including the locking device;

FIG. 34 is an enlarged perspective view of the distal end of the axialdrive assembly shown in FIG. 31;

FIG. 35 is an enlarged perspective view of the distal end of theelongated body of the stapling apparatus shown in FIG. 1;

FIG. 36 is an enlarged perspective view of the locking device shown inFIG. 33;

FIG. 37 is an enlarged perspective view of a lower housing half of theproximal housing portion of the disposable loading unit shown in FIG.27;

FIG. 38 is a side cross-sectional view of the disposable loading unitshown in FIG. 20;

FIG. 39 is an enlarged view of the indicated area of detail shown inFIG. 38;

FIG. 40 is a perspective view of the surgical stapling apparatus shownin FIG. 1 with the disposable loading unit of FIG. 19 detached from theelongated body;

FIG. 41 is an enlarged perspective view of the disposable loading unitof FIG. 19 during attachment to the elongated body of the surgicalstapling apparatus shown in FIG. 1;

FIG. 42 is another enlarged perspective view of the disposable loadingunit of FIG. 19 during attachment to the elongated body of the surgicalstapling apparatus shown in FIG. 1;

FIG. 43 is a cross-sectional view taken along section line 43-43 of FIG.41;

FIG. 43 a is a side cross-sectional view of the rotation knob,articulation mechanism, and sensing mechanism during insertion of adisposable loading unit into the elongated body of the surgical staplingapparatus;

FIG. 44 is a cross-sectional view taken along section line 44-44 of FIG.42;

FIG. 45 is a side cross-sectional view of the distal end of thedisposable loading unit of FIG. 1 with tissue positioned between theanvil and clamp assemblies;

FIG. 46 is a side cross-sectional view of the handle assembly with themovable handle in an actuated position;

FIG. 47 is an enlarged view of the indicated area of detail shown inFIG. 46;

FIG. 48 is a cross-sectional view of the proximal end of the disposableloading unit of FIG. 19 and the distal end of the elongated body of thesurgical stapling apparatus shown in FIG. 1 with the control rod in apartially advanced position;

FIG. 49 is a cross-sectional view of the tool assembly of the surgicalstapling apparatus shown in FIG. 1 positioned about tissue in theclamped position;

FIG. 50 is a cross-sectional view of the handle assembly of the staplingapparatus of FIG. 1 during the clamping stroke of the apparatus;

FIG. 51 is a side cross-sectional view of the distal end of the toolassembly of the stapling apparatus shown in FIG. 1 during firing of theapparatus;

FIG. 52 is a side cross-sectional view of the distal end of the toolassembly of the stapling apparatus shown in FIG. 1 after firing of theapparatus;

FIG. 53 is a side cross-sectional view of the handle assembly of theapparatus during retraction of the actuation shaft;

FIG. 54 is a side cross-sectional view of the handle assembly of thestapling apparatus during actuation of the emergency release button;

FIG. 55 is a top view of the articulation mechanism of the surgicalstapling apparatus;

FIG. 56 is a side cross-sectional view of the articulation mechanism androtation member of the surgical stapling apparatus shown in FIG. 1;

FIG. 57 is a top view of the distal end of the elongated body, themounting assembly, and the proximal end of the tool assembly duringarticulation of the stapling apparatus;

FIG. 58 is a perspective view of the surgical stapling apparatus duringarticulation of the tool assembly;

FIG. 59 is a perspective view of the surgical stapling apparatus duringarticulation and rotation of the tool assembly;

FIG. 60 is a top view of the distal end of the disposable loading unitimmediately prior to articulation;

FIG. 61 is a top view of the distal end of the elongated body, themounting assembly, and the proximal end of the tool assembly duringarticulation of the stapling apparatus;

FIG. 62 is a partial cross-sectional view of a portion of the disposableloading unit during retraction of the locking device; and

FIG. 63 is a partial cross-sectional view of a portion of the disposableloading unit with the locking device in the locked position.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

Preferred embodiments of the presently disclosed endoscopic surgicalstapling apparatus will now be described in detail with reference to thedrawings, in which like reference numerals designate identical orcorresponding elements in each of the several views.

In the drawings and in the description that follows, the term“proximal”, as is traditional, will refer to the end of the staplingapparatus which is closest to the operator, while the term distal willrefer to the end of the apparatus which is furthest from the operator.

FIGS. 1-3 illustrate one embodiment of the presently disclosed surgicalstapling apparatus shown generally as 10. Briefly, surgical staplingapparatus 10 includes a handle assembly 12 and an elongated body 14. Adisposable loading unit or DLU 16 is releasably secured to a distal endof elongated body 14. Disposable loading unit 16 includes a toolassembly 17 having a cartridge assembly 18 housing a plurality ofsurgical staples and an anvil assembly 20 movably secured in relation tocartridge assembly 18. Disposable loading unit 16 is configured to applylinear rows of staples measuring from about 30 mm to about 60 mm inlength. Disposable loading units having linear rows of staples of otherlengths are also envisioned, e.g., 45 mm. Handle assembly 12 includes astationary handle member 22, a movable handle member 24, and a barrelportion 26. A rotatable member 28 is preferably mounted on the forwardend of barrel portion 26 to facilitate rotation of elongated body 14with respect to handle assembly 12. An articulation lever 30 is alsopreferably mounted on the forward end of barrel portion 26 adjacentrotatable knob 28 to facilitate articulation of tool assembly 17. A pairof retraction knobs 32 are movably positioned along barrel portion 26 toreturn surgical stapling apparatus 10 to a retracted position, as willbe described in detail below.

Referring to FIG. 4, handle assembly 12 includes housing 36, which ispreferably formed from molded housing half-sections 36 a and 36 b, whichforms stationary handle member 22 and barrel portion 26 of handleassembly 12 (See FIG. 1). Movable handle member 24 is pivotablysupported between housing half-sections 36 a and 36 b about pivot pin38. A biasing member 40, which is preferably a torsion spring, biasesmovable handle 24 away from stationary handle 22. An actuation shaft 46is supported within barrel portion 26 of housing 36 and includes atoothed rack 48. A driving pawl 42 having a rack engagement finger 43with laterally extending wings 43 a and 43 b is pivotably mounted to oneend of movable handle 24 about a pivot pin 44. A biasing member 50,which is also preferably a torsion spring, is positioned to urgeengagement finger 43 of driving pawl 42 towards toothed rack 48 ofactuation shaft 46. Movable handle 24 is pivotable to move engagementfinger 43 of driving pawl 42 into contact with toothed rack 48 ofactuation shaft 46 to advance the actuation shaft linearly in the distaldirection. The forward end of actuation shaft 46 rotatably receives theproximal end 49 of a control rod 52 such that linear advancement ofactuation shaft 46 causes corresponding linear advancement of controlrod 52. A locking pawl 54 having a rack engagement member 55 ispivotably mounted within housing 36 about pivot pin 57 and is biasedtowards toothed rack 48 by biasing member 56, which is also preferably atorsion spring. Engagement member 55 of locking pawl 54 is movable intoengagement with toothed rack 48 to retain actuation shaft 46 in alongitudinally fixed position.

A retraction mechanism 58 which includes a pair of retractor knobs 32(See FIG. 1) is connected to the proximal end of actuation shaft 46 by acoupling rod 60. Coupling rod 60 includes right and left engagementportions 62 a and 62 b for receiving retractor knobs 32 and a centralportion 62 c which is dimensioned and configured to translate within apair of longitudinal slots 34 a formed in actuation shaft 46 adjacentthe proximal end thereof. A release plate 64 is operatively associatedwith actuation shaft 46 and is mounted for movement with respect theretoin response to manipulation of retractor knobs 32. A pair of spacedapart pins 66 extend outwardly from a lateral face of actuation shaft 46to engage a pair of corresponding angled cam slots 68 formed in releaseplate 64. Upon rearward movement of retractor knobs 32, pins 66 canrelease plate 64 downwardly with respect to actuation shaft 46 and withrespect to toothed rack 48 such that the bottom portion of release plate64 extends below toothed rack 48 to disengage engagement finger 43 ofdriving pawl 42 from toothed rack 48. A transverse slot 70 is formed atthe proximal end of release plate 64 to accommodate the central portion62 c of coupling rod 60, and elongated slots 34 (See FIG. 1) are definedin the barrel section 26 of handle assembly 12 to accommodate thelongitudinal translation of coupling rod 60 as retraction knobs 32 arepulled rearwardly to retract actuation shaft 46 and thus retract controlrod 52 rearwardly. Actuation shaft 46 is biased proximally by spring 72which is secured at one end to coupling rod portion 62 via connector 74and at the other end to post 76 on actuation shaft 46.

Referring also to FIG. 5, handle assembly 12 includes a firing lockoutassembly 80 which includes a plunger 82 and a pivotable locking member83. Plunger 82 is biased to a central position by biasing springs 84 andincludes, annular tapered camming surfaces 85. Each end of plunger 82extends through housing 36 (See FIG. 1) adjacent an upper end ofstationary handle 22. Pivotable locking member 83 is pivotably attachedat its distal end between housing half-sections 36 a and 36 b aboutpivot pin 86 and includes a locking surface 88 and proximal extension 90having a slot 89 formed therein. Locking member 83 is biased by spring92 counter-clockwise (as viewed in FIG. 4) to move locking surface 88 toa position to abut the distal end of actuation shaft 46 to preventadvancement of shaft 46 and subsequent firing of stapling apparatus 10.Annular tapered camming surface 85 is positioned to extend into taperedslot 89 in proximal extension 90. Lateral movement of plunger 82 ineither direction against the bias of either spring 84 moves taperedcamming surface 85 into engagement with the sidewalls of tapered slot 89to pivot locking member 83 clockwise about pivot pin 86, as viewed inFIG. 4, to move blocking surface 88 to a position to permit advancementof actuation shaft 46 and thus firing of stapling apparatus 10. Blockingsurface 88 is retained in this position by recesses 87 which receive thetapered tip of camming surface 85 to lock locking member 83 in acounter-clockwise position. Operation of firing lockout assembly 80 willbe further illustrated below.

Referring to FIGS. 4, 6, and 7, handle mechanism 12 also includes ananti-reverse clutch mechanism which includes a first gear 94 rotatablymounted on a first shaft 96, and second gear 98 mounted on a secondshaft 100, and a slide plate 102 (FIGS. 6 and 7) slidably mounted withinhousing 36. Slide plate 102 includes an elongated slot 104 dimensionedand configured to be slidably positioned about locking pawl pivot pin57, a gear plate 106 configured to mesh with the teeth of second gear98, and a cam surface 108. In the retracted position, cam surface 108 ofslide plate 102 engages locking pawl 54 to prevent locking pawl 54 fromengaging toothed rack 48. Actuation shaft 46 includes a distal set ofgear teeth 110 a spaced from a proximal set of gear teeth 110 bpositioned to engage first gear 94 of actuation shaft 46 during movementof actuation shaft 46. When actuation shaft 46 is advanced by pivotingmovable handle 24 about pivot pin 38, distal gear teeth 110 a onactuation shaft 46 mesh with and rotate first gear 94 and first shaft96. First shaft 96 is connected to second shaft 100 by spring clutchassembly such that rotation of first shaft 96 will cause correspondingrotation of second shaft 100. Rotation of second shaft 100 causescorresponding rotation of second gear 98 which is engaged with gearplate 106 on slide plate 102 to cause linear advancement of slide plate102. Linear advancement of slide plate 102 is limited to the length ofelongated slot 104. When slide plate has been advanced the length ofslot 104, cam surface 108 releases locking pawl 54 such that it is movedinto engagement with toothed rack 48. Continued advancement of actuationshaft 46 eventually moves gear teeth 110 b into engagement with gearplate 106. However, since slide plate 102 is longitudinally fixed inposition, the spring clutch is forced to release, such that continueddistal advancement of actuation shaft 46 is permitted.

When actuation shaft 46 is returned to the retracted position (bypulling retraction knobs 34 proximally, as discussed above) gear teeth110 b engage first gear 94 to rotate second gear 98 in the reversedirection to retract slide member 102 proximally within housing 36.Proximal movement of slide member 102 advances cam surface 108 intolocking pawl 54 prior to engagement between locking pawl 54 and toothedrack 48 to urge locking pawl 54 to a position to permit retraction ofactuation shaft 46.

Referring again to FIG. 4, handle assembly 12 includes an emergencyreturn button 112 pivotally mounted within housing 36 about a pivotmember 114 supported between housing half-sections 36 a and 36 b. Returnbutton 112 includes an externally positioned member 116 positioned onthe proximal end of barrel portion 26. Member 116 is movable about pivotmember 114 into engagement with the proximal end of locking pawl 54 tourge rack engagement member 55 out of engagement with toothed rack 48 topermit retraction of actuation shaft 46 during the firing stroke of thestapling apparatus 10. As discussed above, during the clamping portionof advancement of actuation shaft 46, slide plate 102 disengages pawl 54from rack 48 and thus actuation of return button 112 is not necessary toretract the actuation shaft 46.

FIG. 8 illustrates the interconnection of elongated body 14 and handleassembly 12. Referring to FIGS. 8-10, housing 36 includes an annularchannel 117 configured to receive an annular rib 118 formed on theproximal end of rotation member 28, which is preferably formed frommolded half-sections 28 a and 28 b. Annular channel 117 and rib 118permit relative rotation between rotation member 28 and housing 36.Elongated body 14 includes inner housing 122 and an outer casing 124.Inner housing 122 is dimensioned to be received within outer casing 124and includes an internal bore 126 (FIG. 8) which extends therethroughand is dimensioned to slidably receive a first articulation link 123 andcontrol rod 52. The proximal end of housing 122 and casing 124 eachinclude a pair of diametrically opposed openings 130 and 128,respectively, which are dimensioned to receive radial projections 132formed on the distal end of rotation member 28. Projections 132 andopenings 128 and 130 fixedly secure rotation member 28 and elongatedbody 14 in relation to each other, both longitudinally and rotatably.Rotation of rotation knob 28 with respect to handle assembly 12 thusresults in corresponding rotation of elongated body 14 with respect tohandle assembly 12.

An articulation mechanism 120 is supported on rotatable member 28 andincludes articulation lever 30, a cam member 136, a translation member138, and first articulation link 123 (FIG. 9). Articulation lever 30 ispivotably mounted about pivot member 140 which extends outwardly fromrotation member 28 and is preferably formed integrally therewith. Aprojection 142 extends downwardly from articulation lever 30 forengagement with cam member 136.

Referring temporarily to FIGS. 11 and 12, cam member 136 includes ahousing 144 having an elongated slot 146 extending through one sidethereof and a stepped camming surface 148 formed in the other sidethereof. Each step of camming surface 148 corresponds to a particulardegree of articulation of stapling apparatus 10. Although five steps areillustrated, fewer or more steps may be provided. Elongated slot 146 isconfigured to receive projection 142 formed on articulation lever 30.Housing 144 includes a distal stepped portion 150 and a proximal steppedportion 152. Proximal stepped portion 152 includes a recess 154.

Referring again to FIGS. 8-10 and also to FIGS. 13-15, translationmember 138 includes a plurality of ridges 156 which are configured to beslidably received within grooves 158 formed along the inner walls ofrotation member 28. Engagement between ridges 156 and grooves 158prevent relative rotation of rotation member 28 and translation member138 while permitting relative linear movement. The distal end oftranslation member 138 includes arm 160 which includes an opening 162configured to receive a finger 164 extending from the proximal end ofarticulation link 123 (See FIG. 10 a). A pin 166 having a housing 168constructed from a non-abrasive material, e.g., teflon, is secured totranslation member 138 and dimensioned to be received within steppedcamming surface 148.

In an assembled condition, proximal and distal stepped portions 150 and152 of cam member 136 are positioned beneath flanges 170 and 172 formedon rotation member 28 to restrict cam member 136 to transverse movementwith respect to the longitudinal axis of stapling apparatus 10. Whenarticulation lever 30 is pivoted about pivot member 140, cam member 136is moved transversely on rotation member 28 to move stepped cammingsurface 148 transversely relative to pin 166, forcing pin 166 to moveproximally or distally along stepped cam surface 148. Since pin 166 isfixedly attached to translation member 138, translation member 138 ismoved proximally or distally to effect corresponding proximal or distalmovement of first actuation link 123.

Referring to FIGS. 8-10 and 16, a disposable loading unit sensingmechanism extends within stapling apparatus 10 from elongated body 14into handle assembly 12. The sensing mechanism includes a sensor tube176 which is slidably supported within bore 26 of elongated body 14. Thedistal end of sensor tube 176 is positioned towards the distal end ofelongated body 14 and the proximal end of sensor tube 176 is securedwithin the distal end of a sensor cylinder 176 via a pair of nubs 180.The distal end of a sensor link 182 is secured to the proximal end ofsensor cylinder 178. Sensor link 182 (See FIGS. 8 a and 8 c) has abulbous end 184 which engages a camming surface 83 a on pivotablelocking member 83. When a disposable loading unit (not shown) isinserted in the distal end of elongated body 14, the disposable loadingunit engages the distal end 177 of sensor tube 176 to drive sensor tube176 proximally, and thereby drive sensor cylinder 178 and sensor link182 proximally. Movement of sensor link 182 proximally causes bulbousend 184 of sensor link 182 to move distally of camming surface 83 a toallow locking member 83 to pivot under the bias of spring 92 from aposition permitting firing of stapling apparatus 10 to a blockingposition, wherein blocking member 83 is positioned to engage actuationshaft 46 and prevent firing of stapling apparatus 10. Sensor link 182and locking member 83 function to prevent firing of surgical staplingapparatus 10 after a disposable loading unit has been secured toelongated body 14, without first operating firing lockout assembly 80.It is noted that movement of link 182 proximally permits locking member83 to move to its position shown in FIG. 5.

Referring again to FIGS. 9-12, cam member 136 includes recess 154. Alocking ring 184 having a nub portion 186 configured to be receivedwithin recess 154 is positioned about sensor cylinder 178 between acontrol tab portion 188 and a proximal flange portion 190. A spring 192positioned between flange portion 190 and locking ring 184 urges lockingring distally about sensor cylinder 178. When an articulating disposableloading unit 16 b having an extended insertion tip 193 is inserted intothe distal end of elongated body 14 of stapling apparatus 10, insertiontip 193 causes tab portion 188 to move proximally into engagement withlocking ring 184 to urge locking ring 184 and nub 186 proximally ofrecess 154 in cam member 136 (See FIG. 12 b). With nub 186 positionedproximally of recess 154, cam member 136 is free to move transversely toeffect articulation of stapling apparatus 10. A non-articulatingdisposable loading unit does not have an extended insertion tip (SeeFIG. 12 a). As such, when a non-articulating disposable loading unit isinserted in elongated body 14, sensor cylinder 178 is not retractedproximally a sufficient distance to move nub 186 from recess 154. Thus,cam member 136 is prevented from moving transversely by nub 186 oflocking ring 184 which is positioned in recess 154 and articulationlever 30 is locked in its central position.

Referring to FIGS. 16-18, the distal end of elongated body 14 includes acontrol rod locking mechanism 190 which is activated during insertion ofa disposable loading unit into elongated body 14. Control rod lockingmechanism 190 includes a blocking plate 192 which is biased distally bya spring 194 and includes a proximal finger 189 having angled camsurface 195. A semi-circular engagement member 196 is biasedtransversely towards control rod 52 by a spring 197. Control rod 52includes an annular recess 199 configured to receive engagement member196. Blocking plate 192 is movable from a distal position spaced fromengagement member 196 to a proximal position located behind engagementmember 196. In the proximal position, engagement member 196 is preventedfrom being biased from recess 199 by engagement with blocking plate 192.During insertion of a disposable loading unit 16 (See FIG. 1) into thedistal end of elongated body 14, as will be described in further detailbelow, cam surface 195 of blocking plate 192 is engaged by a nub 254(FIG. 30) on the disposable loading unit 16 as the disposable loadingunit is rotated into engagement with elongated body 14 to urge plate 192to the proximal position. Engagement member 196, which is positionedwithin recess 199, is retained therein by blocking plate 192 while nub254 engages cam surface 195 to prevent longitudinal movement of controlrod 52 during assembly. When the disposable loading unit 16 is properlypositioned with respect to the elongated body 14, nub 254 on theproximal end of the disposable loading unit 16 passes off cam surface195 allowing spring 194 to return blocking plate 192 to its distalposition to permit subsequent longitudinal movement of control rod 52.It is noted that when the disposable loading unit nub passes off camsurface 195, an audible clicking sound is produced indicating that thedisposable loading unit 16 is properly fastened to the elongated body14.

Referring to FIGS. 19 and 20, disposable loading unit 16 includes aproximal housing portion 200 adapted to releasably engage the distal endof body portion 14 (FIG. 1). A mounting assembly 202 is pivotallysecured to the distal end of housing portion 200, and is configured toreceive the proximal end of tool assembly 17 such that pivotal movementof mounting assembly 202 about an axis perpendicular to the longitudinalaxis of housing portion 200 effects articulation of tool assembly 17.

Referring to FIGS. 21-26, tool assembly 17 preferably includes anvilassembly 20 and cartridge assembly 18. Anvil assembly 20 includes anvilportion 204 having a plurality of staple deforming concavities 206 (FIG.22) and a cover plate 208 secured to a top surface of anvil portion 204to define a cavity 210 (FIG. 24) therebetween. Cover plate 208 isprovided to prevent pinching of tissue during clamping and firing ofstapling apparatus 10. Cavity 210 is dimensioned to receive a distal endof an axial drive assembly 212 (See FIG. 27). A longitudinal slot 214extends through anvil portion 204 to facilitate passage of retentionflange 284 of axial drive assembly 212 into the anvil cavity 210. Acamming surface 209 formed on anvil portion 204 is positioned to engageaxial drive assembly 212 to facilitate clamping of tissue 198. A pair ofpivot members 211 formed on anvil portion 204 are positioned withinslots 213 formed in carrier 216 to guide the anvil portion between theopen and clamped positions. A pair of stabilizing members 215 engage arespective shoulder 217 formed on carrier 216 to prevent anvil portion204 from sliding axially relative to staple cartridge 220 as cammingsurface 209 is deformed.

Cartridge assembly 18 includes a carrier 216 which defines an elongatedsupport channel 218. Elongated support channel 218 is dimensioned andconfigured to receive a staple cartridge 220. Corresponding tabs 222 andslots 224 formed along staple cartridge 220 and elongated supportchannel 218 function to retain staple cartridge 220 within supportchannel 218. A pair of support struts 223 formed on staple cartridge 220are positioned to rest on side walls of carrier 216 to further stabilizestaple cartridge 220 within support channel 218.

Staple cartridge 220 includes retention slots 225 for receiving aplurality of fasteners 226 and pushers 228. A plurality of spaced apartlongitudinal slots 230 extend through staple cartridge 220 toaccommodate upstanding cam wedges 232 of actuation sled 234. A centrallongitudinal slot 282 extends along the length of staple cartridge 220to facilitate passage of a knife blade 280. During operation of surgicalstapler 10, actuation sled 234 translates through longitudinal slots 230of staple cartridge 220 to advance cam wedges 232 into sequentialcontact with pushers 228, to cause pushers 228 to translate verticallywithin slots 224 and urge fasteners 226 from slots 224 into the stapledeforming cavities 206 of anvil assembly 20.

Referring to FIGS. 27 and 28, mounting assembly 202 includes upper andlower mounting portions 236 and 238. Each mounting portion includes athreaded bore 240 on each side thereof dimensioned to receive threadedbolts 242 (See FIG. 21) for securing the proximal end of carrier 216thereto. A pair of centrally located pivot members 244 (See FIG. 21)extends between upper and lower mounting portions via a pair of couplingmembers 246 which engage the distal end of housing portion 200. Couplingmembers 246 each include an interlocking proximal portion 248 configuredto be received in grooves 250 formed in the proximal end of housingportion 200 to retain mounting assembly 202 and housing portion 200 in alongitudinally fixed position in relation thereto.

Housing portion 200 of disposable loading unit 16 includes an upperhousing half 250 and a lower housing half 252 contained within an outercasing 251. The proximal end of housing half 250 includes engagementnubs 254 for releasably engaging elongated body 14 and an insertion tip193. Nubs 254 form a bayonet type coupling with the distal end of body14 which will be discussed in further detail below. Housing halves 250and 252 define a channel 253 for slidably receiving axial drive assembly212. A second articulation link 256 is dimensioned to be slidablypositioned within a slot 258 formed between housing halves 250 and 252.A pair of blow out plates 255 are positioned adjacent the distal end ofhousing portion 200 adjacent the distal end of axial drive assembly 212to prevent outward bulging of drive assembly 212 during articulation oftool assembly 17. Each blow-out plate 255, as illustrated in FIGS. 27,57, 60 and 61, includes a planar surface which is substantially parallelto the pivot axis of tool assembly 17 and is positioned on a side ofdrive assembly 212 and the pivot axis to prevent outward bulging ofdrive assembly 212. Each blow-out plate includes a first distal bend 255a which is positioned in a respective first groove 202 a formed inmounting assembly 202 and a second proximal bend 255 b which ispositioned in a respective second groove 200 a formed in a distal end ofhousing portion 200.

Referring to FIGS. 29-30, second articulation link 256 includes at leastone elongated metallic plate. Preferably, two or more metallic platesare stacked to form link 256. The proximal end of articulation link 256includes a hook portion 258 configured to engage first articulation link123 (See FIG. 9) and the distal end includes a loop 260 dimensioned toengage a projection 262 formed on mounting assembly 202. Projection 262is laterally offset from pivot pin 244 such that linear movement ofsecond articulation link 256 causes mounting assembly 202 to pivot aboutpivot pins 244 to articulate tool assembly 17.

Referring also to FIGS. 31-34, axial drive assembly 212 includes anelongated drive beam 266 including a distal working head 268 and aproximal engagement section 270. Drive beam 266 may be constructed froma single sheet of material or, preferably, multiple stacked sheets.Engagement section 270 includes a pair of engagement fingers 270 a and270 b which are dimensioned and configured to mountingly engage a pairof corresponding retention slots 272 a and 272 b formed in drive member272. Drive member 272 includes a proximal porthole 274 configured toreceive the distal end 276 of control rod 52 (See FIG. 35) when theproximal end of disposable loading unit 16 is engaged with elongatedbody 14 of surgical stapling apparatus 10.

The distal end of drive beam 266 is defined by a vertical support strut278 which supports a knife blade 280, and an abutment surface 283 whichengages the central portion of actuation sled 234 during a staplingprocedure. Surface 285 at the base of surface 283 is configured toreceive a support member 287 slidably positioned along the bottom of thestaple cartridge 220. Knife blade 280 is positioned to translateslightly behind actuation sled 234 through a central longitudinal slot282 in staple cartridge 220 (FIG. 30) to form an incision between rowsof stapled body tissue. A retention flange 284 projects distally fromvertical strut 278 and supports a cylindrical cam roller 286 at itsdistal end. Cam roller 286 is dimensioned and configured to engage camsurface 209 on anvil body 204 to clamp anvil portion 204 against bodytissue.

Referring also to FIGS. 36-39, a locking device 288 is pivotally securedto drive member 270 about a pivot pin 290. Locking device 288 includes apair of elongate glides 292 and 294 which define a channel 296. A web298 joins a portion of the upper surfaces of glides 292 and 294, and isconfigured and dimensioned to fit within elongated slot 298 formed indrive beam 266 at a position distal of drive member 270. Horizontal cams300 and 302 extend from glides 292 and 294 respectively, and areaccommodated along an inner surface of lower housing half 252. As bestshown in FIG. 42, a torsion spring 304 is positioned adjacent drivemember 270 and engages horizontal cams 300 and 302 of locking device 288to normally bias locking device 288 downward toward lower housing half252 onto ledge 310. Locking device 288 translates through housingportion 200 with axial drive assembly 212. Operation of locking device288 will be described below.

Sequence of Operation

Referring to FIGS. 40-44, to use stapling instrument 10, a disposableloading unit 16 is first secured to the distal end of elongated body 14.As discussed above, stapling instrument 10 can be used with articulatingand non-articulating disposable loading units having linear rows ofstaples between about 30 mm and about 60 mm. To secure disposableloading unit 16 to elongated body 14, the distal end 276 of control rod52 is inserted into insertion tip 193 of disposable loading unit 16, andinsertion tip 193 is slid longitudinally into the distal end ofelongated body 14 in the direction indicated by arrow “A” in FIG. 41such that hook portion 258 of second articulation link 256 slides withina channel 310 in elongated body 314. Nubs 254 will each be aligned in arespective channel (not shown) in elongated body 14. When hook portion258 engages the proximal wall 312 of channel 310, disposable loadingunit 16 is rotated in the direction indicated by arrow “B” in FIGS.41-44 to move hook portion 258 of second articulation link 256 intoengagement with finger 164 of first articulation link 123. Nubs 254 alsoforms a bayonet type coupling within annular channel 314 in body 14.During rotation of loading unit 16, nubs 254 engage cam surface 195(FIG. 41) of block plate 192 to initially move plate 192 in thedirection indicated by arrow “C” in FIGS. 41 and 43 to lock engagementmember 196 in recess 199 of control rod 52 to prevent longitudinalmovement of control rod 52 during attachment of disposable loading unit16. During the final degree of rotation, nubs 254 disengage from camsurface 195 to allow blocking plate 192 to move in the directionindicated by arrow “D” in FIGS. 42 and 44 from behind engagement member196 to once again permit longitudinal movement of control rod 52.

Referring to FIGS. 43 and 43 a, when insertion tip 193 engages thedistal end of sensor tube 176, the disposable loading unit sensingmechanism is actuated. Insertion tip 193 engages and moves sensor tube176 proximally in the direction indicated by arrow “E” in FIG. 43. Asdiscussed above, proximal movement of sensor tube 176 effects proximalmovement of sensor cylinder 178 and sensor link 182 in the directionindicated by arrow “E” in FIG. 43 a to pivot locking member 83counter-clockwise, as indicated by arrow “Y” in FIG. 43 a, from anon-blocking position to a position blocking movement of actuation shaft46.

Referring to FIGS. 46-49, with a disposable loading unit attached tostapling instrument 10, tool assembly 17 can be positioned about tissue320 (FIG. 45). To clamp tissue between anvil assembly 20 and cartridgeassembly 18, stationary handle 24 is moved in the direction indicated byarrow “E” in FIG. 46 against the bias of torsion spring 40 to movedriving pawl 42 into engagement with shoulder 322 on actuation shaft 46.Engagement between shoulder 322 and driving pawl 42 advances actuationshaft 46 and thus advances control rod 52 distally. Control rod 52 isconnected at its distal end to axial drive assembly 212 (FIG. 48),including drive beam 266, such that distal movement of control rod 52effects distal movement of drive beam 266 in the direction indicated byarrow “F” in FIGS. 48 and 49, moving cam roller 286 into engagement withcam surface 209 on anvil portion 204 to urge anvil portion 204 in thedirection indicated by arrow “G” in FIG. 49. It is noted that onecomplete stroke of movable handle 24 advances actuation shaft 46approximately 15 mm which is sufficient to clamp tissue during the firststroke but not to fire staples.

As discussed above with respect to the anti-reverse clutch mechanism,during the first (clamping) stroke of movable handle 24, slide plate 102(FIG. 46) prevents locking pawl 54 from engaging toothed rack 48. Tomaintain actuation shaft 46 in its longitudinal position after handle 24is released, an engagement member 324 (FIG. 47) is provided on lockingmember 83 to engage shoulder 326 on actuation shaft 46 and retain shaft46 in its longitudinal position (See FIG. 47). Upon release of movablehandle 24, drive pawl 42 moves over rack 48 as torsion spring 40 returnshandle 24 to a position spaced from stationary handle 22. In thisposition, driving pawl 42 is urged into engagement with toothed rack 48to retain actuation shaft 46 in its longitudinal fixed position.

In order to fire staples, movable handle 24 is actuated again, i.e.,moved through another stroke. As discussed above, stapling apparatus 10is capable of receiving disposable loading units having linear rows ofstaples of between about 30 mm and about 60 mm. Since each stroke of themovable handle 24 preferably advances actuation shaft 46 15 mm, and onestroke is required to clamp tissue, the movable handle must be actuated(n+1) strokes to fire staples, where n is the length of the linear rowsof staples in the disposable loading unit attached to staplinginstrument 10 divided by 15 mm.

Referring to FIG. 50, prior to being able to fire staples, firinglockout assembly 80 (FIG. 4) must be actuated to move locking surface 88from its blocking position (FIG. 47) to a non-blocking position. This isaccomplished by pressing down on plunger 82 to move camming surface 85into engagement with sidewalls of slot 89 of locking member 83 to pivotlocking member 83 in the direction indicated by arrow “G” in FIG. 50(see also FIG. 5). Thereafter, movable handle 24 may be actuated anappropriate number of strokes to advance actuation shaft 46, and thuscontrol rod 52 and drive beam 266, distally in the direction indicatedby arrow “H” in FIGS. 51 and 52 to advance actuation sled 234 throughstaple cartridge 220 to effect ejection of staples. It is noted thatafter the first or clamping stroke of movable handle 54 (during thesecond stroke), slide 102 passes over locking pawl 54 allowing torsionspring 56 to move locking pawl 54 in the direction indicated by arrow“I” in FIG. 50 into engagement with toothed rack 48 to retain actuationshaft 46 in its longitudinal position.

Referring to FIG. 53, to retract actuation shaft 46 and thus control rod52 and drive member 266 after firing staples, retraction knobs 32 (seeFIG. 1) are pulled proximally causing pins 66 to move release plate 64in the direction indicated by arrow “J” in FIG. 53 over teeth 48 todisengage drive pawl 42 from engagement with teeth 48. As discussedabove, with respect to the anti-reverse clutch mechanism, locking pawl54 is urged by slide plate 102 out of engagement with toothed rack 48(not shown) to permit actuation shaft 46 to be moved proximally, in thedirection indicated by arrow “L”, after drive pawl 42 is disengaged fromteeth 48.

Referring to FIG. 54, in order to retract actuation shaft 46 prior tofiring stapling apparatus, i.e., when locking pawl is currently engagedwith toothed racked 48, emergency return button 112 is pushed in thedirection indicated by arrow “Z” in FIG. 54 to disengage locking pawl 54from toothed rack 48. Retraction knobs 32 (FIG. 1) must also beconcurrently pulled rearwardly, as discussed above, to release drivepawl 42 from rack 48.

Referring to FIGS. 55-61, when an articulating disposable loading unitis secured to elongated body 14 and articulation lever 30 is pivoted inthe direction indicated by arrow “M” in FIG. 55, cam member 136 is movedtransversely by projection 142 (FIG. 10) in the direction indicated byarrow “N” between flanges 170 and 172 of rotation knob 28. Sincetranslation member 138 is prevented from rotating by ridges 156 (FIG.13), pin 166, which is fixedly secured to translation member 138, isforced to move along stepped cam surface 148. Movement of pin 166 causescorresponding movement of translation member 138 in the directionindicated by arrow “P” in FIGS. 55 and 56 to advance first articulationlink 123 in the distal direction. The distal end of first articulationlink 123 engages the proximal end of second articulation link 256 (FIG.42) which is connected to projection 262 on mounting assembly 202 toadvance second link 256 in the direction indicated by arrow “Q” in FIG.57. Projection 262 is laterally offset from pivot members 244, such thatdistal advancement of second articulation link 256 causes mountingassembly 202 and thus tool assembly 17 to pivot in the directionindicated by arrow “R” in FIGS. 57 and 58. Note in FIG. 59 that rotationmember 28 can be rotated to rotate elongated body 14 about itslongitudinal axis while tool assembly 17 is articulated.

FIGS. 60-61 illustrate articulation of tool assembly 17 in the oppositedirection to that described above. When second articulation link 256 isretracted by rotating articulation lever 30 in a counter-clockwisedirection (not shown) as viewed in FIG. 55, pin 66 is forced to moveproximally along stepped camming surface 148, moving translation member138 and first articulation link 123 proximally. Movement of firstarticulation link 123 proximally, causes second articulation link 256 tomove proximally as indicated by arrow “S” in FIG. 58, to rotate toolassembly 17 in a clockwise direction, as indicated by arrow “T” in FIG.61.

Referring to FIG. 12, movement of pin 166 (FIG. 9) between adjacent stepportions 340 causes tool assembly 17 to articulate 22.5 degrees. Cammingsurface 148 includes five step portions 340. The third step portioncorresponds to the non-articulated tool assembly position, whereas thefirst and the fifth step portions correspond to articulation of toolassembly 17 to forty-five degrees. Each step portion is flat to retainarticulation lever 30 in a fixed position when pin 166 is engagedtherewith.

Referring now to FIGS. 37, 39, 62 and 63, the sequence of lockoutoperation will be described in detail. In FIG. 39, lockout device 288 isshown in its prefired position with horizontal cams 300 and 302 restingon top of projections 330 formed in the sidewalls of lower housing half252 (FIG. 37). In this position, locking device 288 is held up out ofalignment with projection 332 formed in the bottom surface of lowerhousing half 252, and web 298 is in longitudinal juxtaposition withshelf 334 defined in drive beam 266. This configuration permits theanvil 20 (FIG. 38) to be opened and repositioned onto the tissue to bestapled until the surgeon is satisfied with the position withoutactivating locking device 288 to disable the disposable loading unit 16.

As shown in FIG. 62, upon distal movement of drive beam 266, lockingdevice 288 rides off of projections 330 (not shown) and is biased intoengagement with base lower housing half 252 by spring 304, distal toprojection 332. Locking device 288 remains in this configurationthroughout firing of the apparatus.

Upon retraction of the drive beam 266 in the direction indicated byarrow “U” in FIG. 62, locking device 288 passes under projections 330and rides over projection 332 until the distalmost portion of lockingdevice 288 is proximal to projection 332. Spring 304 biases lockingdevice 288 into juxtaposed alignment with projection 332, effectivelydisabling the disposable loading unit. If an attempt is made toreactuate the apparatus, the control rod 52 will abut a proximal endsurface of locking device 288 which surface is diagonally sloped toimpart a moment about pivot pin 342 such that the distal end of lockingdevice 288 is rotationally urged into contact with projection 332.Continued distal force in the direction indicated by arrow “W” in FIG.63, will only serve to increase the moment applied to the locking devicethus the locking device will abut projection 332 and inhibit distalmovement of the control rod 52.

Referring again to FIGS. 41-44, the disabled or locked disposableloading unit can be removed from the distal end of elongated body 14 byrotating disposable loading unit 16 in the direction opposite to thedirection indicated by arrow'“B” in FIGS. 41, 42 and 44, to disengagehook portion 258 of second articulation link 256 from finger 164 offirst articulation link 123, and to disengage nubs 254 from withinchannel 314 of elongated body 14. After rotation, disposable loadingunit 16 can be slid in the direction opposite to that indicated by arrow“A” in FIG. 41 to detach body 14 from disposable loading unit 16.Subsequently, additional articulating and/or non-articulating disposableloading units can be secured to the distal end of elongated body, asdescribed above, to perform additional surgical stapling and/or cuttingprocedures. As discussed above, each disposable loading unit may includelinear rows of staples which vary from about 30 mm to about 60 mm.

It will be understood that various modifications may be made to theembodiments disclosed herein. For example, the stapling apparatus neednot apply staples but rather may apply two part fasteners as is known inthe art. Further, the length of the linear row of staples or fastenersmay be modified to meet the requirements of a particular surgicalprocedure. Thus, the length of a single stroke of the actuation shaftand/or the length of the linear row of staples and/or fasteners within adisposable loading unit may be varied accordingly. Therefore, the abovedescription should not be construed as limiting, but merely asexemplifications of preferred embodiments. Those skilled in the art willenvision other modifications within the scope and spirit of the claimsappended thereto.

1. A surgical stapling apparatus, comprising a tool assembly having anaxial drive assembly including a drive beam having a plurality ofsheets, the tool assembly including a pivot member allowing the toolassembly to articulate, the tool assembly having a movable link thatcontacts a proximal end of the tool assembly at a location offset fromthe pivot member so that movement of the link articulates the toolassembly.
 2. The surgical stapling apparatus according to claim 1,wherein the drive beam has a knife blade.
 3. The surgical staplingapparatus according to claim 1, further comprising a plate positionedadjacent the pivot member to prevent outward bulging of the driveassembly.
 4. The surgical stapling apparatus according to claim 1,wherein the drive beam is an I-beam having an upper surface and a lowersurface.
 5. The surgical stapling apparatus according to claim 4,wherein the tool assembly has jaws and the upper and lower surfaces areused to close the jaws of tool assembly.
 6. The surgical staplingapparatus according to claim 5, wherein the drive beam also closes thejaws.
 7. The surgical stapling apparatus according to claim 1, whereinthe tool assembly includes a cartridge assembly housing a plurality ofsurgical staples and an anvil assembly.
 8. The surgical staplingapparatus according to claim 7, wherein the drive beam has an uppersurface and a lower surface configured to close the jaws of toolassembly.
 9. The surgical stapling apparatus according to claim 1,wherein the cartridge assembly includes a staple cartridge and aplurality of pushers.
 10. The surgical stapling apparatus according toclaim 9, wherein the pushers sequentially fire a plurality of staples.11. The surgical stapling apparatus according to claim 1, wherein theapparatus applies linear rows of staples.
 12. The surgical staplingapparatus according to claim 1, further comprising a handle assembly.13. The surgical stapling apparatus according to claim 12, wherein thehandle assembly is manually actuated.
 14. The surgical staplingapparatus according to claim 12, wherein the handle assembly includes anarticulation handle.
 15. The surgical stapling apparatus according toclaim 12, wherein the handle assembly includes a handle member thatpivots to move a rack.
 16. The surgical stapling apparatus according toclaim 15, wherein the rack moves the drive beam to fire staples.
 17. Thesurgical stapling apparatus according to claim 1, wherein the toolassembly forms part of a replaceable loading unit.